Firefishe has commented on the following diary entries

Answering your question, yes, the river does appear to be rendered correctly. The river feature, itself, appears on my Dakota 20 from the garmin.openstreetmap.nl maps I use in Base Camp. It's just that small area that shows up as all water. The rest of the map seems fine.

The data that server uses is taken from the OSM project, so I don't really know which source is the issue. There is that Invalid Geometry relation #933167, but again, I don't know if that's relevant, or not.

I took a look at some multi-polygon errors using OSM Inspector. Please have a look at Invalid Geometry relation #933167.

This may also be local to the garmin.openstreetmap.nl server, of course, but I just happened to see that error, and it's in roughly the right area of the boundaries I have in question. Perhaps not exact, but I don't know what else it could be.

Again, I'm new, and it will take a while for me to understand how everything is put together.

Thanks for your assistance. I appreciate it.

Oh, and yes, Firefishy is similar, although I do not know the gentleman.